Mobile electronic devices typically include a display to present a user interface (UI) that provides visual information to a user. The UI also generally allows the user to input control and data information to the mobile electronic device. For example, cellular telephones (one type of mobile electronic device) typically have a liquid crystal display (LCD) and a keypad to present a UI that allows the user to make telephone calls, store telephone numbers, find stored phone numbers etc.
Some mobile electronic devices have a “clamshell” design in which the mobile electronic device is separated into two portions attached by a hinge mechanism so that the device can be “opened” and “closed”. In a typical clamshell design, one portion contains the display and the other contains a keypad. When open, the display and keypad are visible to the user. When closed, the display and keypad are typically positioned to face each other so that they are somewhat protected from the environment and not visible to the user.
In some clamshell designs, the mobile electronic device includes a secondary display that is visible to the user when the mobile electronic device is closed. This secondary display typically has limited functionality. For example, in a clamshell type cellular telephone the time and date may be shown on the secondary display or, when receiving a telephone call, the cellular telephone may show the name or telephone number of the caller on the secondary display. In a typical design, a cellular telephone does not provide a UI on the secondary display.
Further, mobile electronic devices are typically battery-powered. Consequently, power conservation is an important design consideration.